Nobody writing about schools has been a bigger supporter of getting more students into eighth-grade algebra than I have been. I wrote a two-part series for the front page six years ago that pointed out how important it is to be able to handle algebra's abstractions and unknown quantities before starting high school. I have argued that we should rate middle schools by the percentage of students who complete Algebra I by eighth grade.

Now, because of a startling study being released today, I am having second thoughts.

Tom Loveless, director of the Brown Center on Education Policy at the Brookings Institution, has looked at the worst math students, those scoring in the bottom 10th on the National Assessment of Educational Progress eighth-grade test. He discovered that 28.6 percent of them -- let me make that clear: nearly three out of every 10 -- were enrolled in first-year algebra, geometry or second-year algebra. Almost all were grossly misplaced, probably because of the push to get kids into algebra sooner.

There were 90 employees in a company last year. This year the number of employees increased by 10 percent. How many employees are in the company this year?

A) 9

B) 81

C) 91

D) 99

E) 100

The correct answer is D. Ten percent of 90 is 9. Add that to 90 and you get 99. How many of the misplaced students got it right? Just 9.8 percent. Not good.

This is a big problem for the region and the nation. Politicians and policymakers have fallen in love with the idea of eighth-grade algebra for all. Their ardor is not likely to cool off soon. California is moving toward making the course mandatory for eighth-graders, a shift Gov. Arnold Schwarzenegger (R) compared to President John F. Kennedy's pledge to put a man on the moon.

Other states and cities are moving in the same direction. In D.C. public schools, 51 percent of eighth-graders tested by NAEP in 2007 said they were enrolled in first-year algebra or above, the fourth-highest percentage in the country. Yet the D.C. average score on the NAEP math test (which is not an algebra test) was lower than the score in every state.

It's not that I haven't been warned about this. Many teachers treat me like their favorite D-plus student. They send me thoughtful e-mails trying to explain, in simple language, where I have gone wrong. I received such a message on this topic two weeks ago from Stu Singer, a retired Fairfax County high school math teacher. He said the practice of trying to get every last kid into eighth-grade algebra "has now grown to a critical and in my opinion detrimental level."

Singer and Loveless say plenty of students are ready for algebra by eighth grade, or sooner. But not everyone is. "One hundred twenty thousand eighth-graders are sitting in advanced math classes even though they score in the bottom 10 percent," Loveless wrote. "They know about as much math as the typical second-grader. They do not know basic arithmetic and cannot correctly answer NAEP items using fractions, decimals, or percents."

Some see the flourishing eighth-grade algebra movement as a triumph for equity. Activist educator Robert Moses calls it "the new civil right." Loveless acknowledged that the misplaced bottom 10th are much more likely to be poor, black or Hispanic and more likely to be in a big urban school than average eighth-graders. Yet the shortcomings of the misplaced students in those urban schools are slowing down algebra classes with hundreds of thousands of well-prepared students "who are also predominantly black, Hispanic or poor."

Suburbanites might think this doesn't affect them. In Maryland, 52 percent of eighth-graders reported taking first-year algebra or a more advanced class. In Virginia, the rate was 42 percent. The national average was 36 percent. Maryland ranked 16th and Virginia eighth among states on the NAEP test. Those results appear strong, but to me and others, they are not strong enough. Check that math problem above. Nationally, only 36.5 percent of eighth-graders and 48.7 percent of those in Algebra I or above answered correctly.

We know math instruction has to improve in lower grades, a subject my colleague Maria Glod explores on this page today. Many people would also argue we should let far fewer eighth-graders try algebra. But such gate-keeping can shut out motivated or suddenly maturing students who surprise their teachers and do well.

It would be better to think of algebra as we do swimming: something everyone should learn, but most importantly learn well. Get everyone into the pool as soon as possible. But let's not mark them as having passed the course until we are sure they can swim several lengths without drowning.